The invention relates to a high-hardness ethylene propylene diene monomer material and a preparation method thereof. The high-hardness ethylene propylene diene monomer material is prepared from the following raw materials in parts by mass: 100 parts of a raw rubber base body, 20-50 parts of a plasticizer, 100-150 parts of carbon black, 1-4 parts of a vulcanizing agent and 1-5 parts of a vulcanization accelerator, wherein the raw rubber base body is a commixture of an ethylene propylene diene monomer and a copolymer of 1,2-syndiotactic polybutadiene and ethylene-vinyl acetate. With the combination of EVA and RB in EPDM, and together with carbon black, the plasticizer, the vulcanizing agent and the vulcanization accelerator, the high-hardness ethylene propylene diene monomer material which is applicable to extrusion production and good in physical mechanical property and weather resistance can be finally prepared, and can be successfully applied to door seals of containers.